Island expert growers give tips on jump-starting seedling growth


For The Beachcomber

My vegetable seedlings have legs. 

As early as Jan. 30, longing to jump-start spring, I planted vegetable seeds in flats. I slid them into my plastic-wrapped “start cart,”  hung gro-lites and — within days — germination!

A month passed: My seedlings grew two inches and stopped, stuck in seed-leaf stage. I wondered why they were so unlike the lush seedlings I saw when a kid, grown by my neighbor, a victory gardener.

So I tracked down 17 Island growers,  professional and hobbyist, to ask how they jump-start seedlings.

• Germinate warm, but grow cool.

Most of the Island’s farmers have greenhouses that capture sunlight and warmth. But in late winter, even a greenhouse needs a boost.

I met Chandler Briggs at Island Meadow Farm on a frosty morning. Like many farmers, he uses bottom heat to get seeds started. Heating coils cover his greenhouse tables, seed trays spread on top. He stuck a thermometer in one flat: 70 degrees, optimum for germination.

“I cover the trays with plastic domes to keep humidity and warmth in,” he said, “but once the seeds germinate, they’re moved to unheated benches for a few weeks.”

Other gardeners set trays near pilot lights, woodstoves, on radiant floors, even in food-warming trays from Granny’s Attic.

Karen Biondo of K-Jo Farm also germinates on heat but uncovers the seedlings once leaves emerge.

“Moisture plus warmth encourages fungal growth, so I take them off heat once they sprout, leaving them in the unheated greenhouse.”

Nancy Lewis-Williams, master gardener and co-instructor with Cathy Fulton of the recent class “Starting a Vegetable Garden,” seconds that. “Use the dome until they sprout thoroughly, then remove it. Get moisture in the soil rather than on the plants,” she said.

• Keep it cool but bright, and enhance your light.

For growing cool-hardy plants such as lettuce, spinach, and peas, most growers said that cool is best.

“Light is key: Keep your environment on the cool side, but bright,” said Rob Peterson of Plum Forest Farm.

When I described the two-inch stems on my pak choi seedlings, Peterson said, “If your growing situation is warm and not very light, the warmth will push seedlings to grow, while your gro-lites give them something to stretch toward.” 

Several gardeners use gro-lites within their greenhouses. Though her greenhouse is in full sun, Biondo uses three gro-lites on overcast days and evenings.

Green Man Farm runs eight fluorescent tubes over its seed-flats, checking daily to make sure the seedlings don’t dry out. (Though fluorescent tubes are cool, their ballasts can warm a space upward of 80 degrees.)

Several gardeners combined gro-lites with a sunny window. March Twisdale has eight gro-lites above her growing shelves, which are pushed against south-facing glass doors.

“The trick is never have the light more than an inch from the plants,” she said.

James Dam holds his gro-lites near a window “so close to the plants I have to raise the lights to water.”

He finds that with more light, his seedlings don’t stretch so tall.

Over and over, gardeners said to do whatever you can to bring light to the seedlings. Peggy Wood washes windows and removes screens. Leda Langley knocks the pollen off her hoophouse.

And push flats against the glass if you use a warm sunny window, says Lewis-Williams. She recommends turning trays daily so seedlings grow straight. 

• Sowing — and growing on

Though the farmers were sowing greens and alliums by early February, home gardeners might wait until mid-March, about four weeks before our last frost date.

“Many gardeners start  too early, then end up nursing seedlings along. Plants only need two to four weeks before going outdoors,”  Langley said.

William Forrester of Green Man Farm agreed, “If you start things too early and then plant them out, they’ll just sit there.”

The quality seedlings I saw, whether grown in greenhouses or on windowsills, seemed to grow one-quarter inch a week. By month’s end, they had one or two pairs of true leaves and were one to two inches high. 

The lettuce at Island Meadow Farm had reached that size; I found Briggs moving trays outside to start hardening them off.

Seedlings grown indoors have soft tissue that needs to toughen through exposure to the elements: a couple hours a day to start, with longer periods daily for two to three weeks. 

Plants so prepared will size up quickly once in the ground, said Peterson of Plum Forest Farm. And his partner, Joanne Jewell, manager of the Vashon Farmers Market, said “If you can’t grow them, VIGA growers will have seedlings for sale.” 

Inspired by good advice, I made a “sun-pit” of masonry block, insulation panel and an old window. I planted a tray of new seedlings and now, a week later, they’re up and not leggy at all.

— Karen Dale is an oil painter who gardens on a sandy hilltop on Vashon’s south end.

Other bits of advice

Use sterile soil, made light with vermiculture, to reduce damping off.

Use fresh seed: Last year’s seed, stored at room temp, may germinate poorly.

Use little or no fertilizer: Too much nitrogen makes seedlings spindly and soft.

Try “chitting” to jump-start corn and beans: Soak seeds for a day, then set them between damp paper; plant when a little “tongue” of root peeks out. 

Be realistic about your land’s “grow-ability.” If your land only offers four hours of direct sun in summer, you might be better off patronizing local farmers.

Just try it. See what your own micro-climate has to offer.

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